Analysis of the Intramuscular Innervation of the Lateral Pterygoid Muscle

The lateral pterygoid muscle has unique anatomical, physiological and functional properties. Since it is attached to the temporomandibular joint (TMJ) disc, its pathologies are closely related to TMJ disorders, which affect many people worldwide. Muscle structures and units are characterized by their morphological appearance, nerve distribution and function. In the present study, we examined the intramuscular innervation pattern of the lateral pterygoid muscle using modified sihler’s method. Two types of innervation pattern were evident. In type I, representing the majority of the samples, a total of three branches arising from the main trunk of the mandibular nerve and the buccal nerve innervated the inferior head of the muscle, while branches from the buccal nerve innervated the superior head. In type II, divisions of the lateral pterygoid nerve branched from the buccal nerve located between the heads of the lateral pterygoid muscle and innervated each head separately. Interestingly, muscle bundles with a stronger tendineous structure showed much more innervation than other parts of the muscle. Future studies including quantitative analysis of the nerve distribution to the muscle bundles are warranted.ope

Clinical and anatomical approach using Sihler's staining technique (whole mount nerve stain).

Sihler's staining allows visualization of the nerve distribution within soft tissues without extensive dissection and does not require slide preparation, unlike traditional approaches. This technique can be applied to the mucosa, muscle, and organs that contain myelinated nerve fibers. In particular, Sihler's technique may be considered the best tool for observing nerve distribution within skeletal muscles. The intramuscular distribution pattern of nerves is difficult to observe through manual manipulation due to the gradual tapering of nerves toward the terminal end of muscles, so it should be accompanied by histological studies to establish the finer branches therein. This method provides useful information not only for anatomists but also for physiologists and clinicians. Advanced knowledge of the nerve distribution patterns will be useful for developing guidelines for clinicians who perform operations such as muscle resection, tendon transplantation, and botulinum toxin injection. Furthermore, it is a useful technique to develop neurosurgical techniques and perform electrophysiological experiments. In this review, Sihler's staining technique is described in detail, covering its history, staining protocol, advantages, disadvantages, and possible applications. The application of this technique for determining the arterial distribution pattern is also described additionally in this study.ope

열린충남 75호-[오피니언2] 강남역 살인사건에 대한 남성이 불편해하는 몇가지 이야기

강남역 노래방 화장실에서 한 여성이 무참히 살해당했다. 여성을 혐오하는 한 남성으로부터. 경찰은 프로파일러를 동원한 조사에서 정신병력을 가진 남성의 '묻지마 살인'으로 잠정 결론을 내렸다. 하지만 남성 피의자의 진술은 '여성혐오'에 맞춰져 있었다. 여성들은 두려워하고 있다. 여성들은 삼삼오오, 강남역 10번 출구로 모였다. 저마다 각각 애도의 뜻을 담은 메모지를 적었고, 국화꽃을 놓았다. 일부 남성들은 불편한 기색을 보였다. 여성이라서 아니라 정신병력을 가진 사람의 소행에 불과한 데 굳이 '여성혐오범죄'로 봐야 하냐는 것이다. 경찰의 범죄 성격을 규정하는 것과는 별개로, 살펴봐야 하는 지점이 있다. -이후 생략-강남역 살인사건에 대한 남성이 불편해하는 몇가지 이야

Clinical implications of the topography of the arteries supplying the medial pterygoid muscle

The literature contains numerous accounts of the muscular anatomy of the medial pterygoid muscle, but little is known about the detailed vascular supply of the muscle. Numerous surgical procedures, such as mandibular ramus osteotomy, angle reduction, and/or parotidectomy, are performed around the muscle in the absence of this information. This study aimed to clarify the arterial supplies to the medial pterygoid muscle to provide critical information for use during various surgical procedures. Detailed dissections were performed on 20 sides of adult cadaveric head and neck specimens after injecting the carotid artery with red liquid neoprene latex. The medial pterygoid muscle was supplied by the following 5 branches of the external carotid artery: (1) the pterygoid artery of the maxillary artery, (2) a direct muscular branch of the facial artery, (3) the ascending palatine artery, (4) an anterior muscular branch of the facial artery, and (5) a previously undescribed muscular branch of the external carotid artery. This analysis of vascular anatomy has revealed new anatomic information on the blood supplies to the medial pterygoid muscle and will be useful to the development of guidelines for preventing hemorrhage during surgical proceduresope

Ultrasound-guided lateral approach for needle insertion into the subscapularis for treatment of spasticity

OBJECTIVE: To evaluate the safety and accuracy of ultrasound (US)-guided needle insertion into the subscapularis using fresh cadavers. DESIGN: A needle was inserted into the subscapularis of adult human cadavers under US guidance using a lateral approach from the posterior axillary fold. An anatomist dissected the cadavers to evaluate the effectiveness of this injection method. SETTING: University dissecting room. PARTICIPANTS: Fresh cadavers (N=5). INTERVENTIONS: US-guided dye injections targeting the motor points of the subscapularis. MAIN OUTCOME MEASURE: Accuracy of the injections and prevalence of complications. The presence of dye within 1.0cm of the motor points was defined as reaching the target. The injection procedure was considered a success if two-thirds of the injected dye reached the target. RESULTS: We did not identify any neurovascular structures at risk of injury in the injection route. All subscapularis muscles were injected successfully using the US-guided lateral approach. CONCLUSIONS: US-guided needle insertion into the subscapularis using this lateral approach was accurate and had the minimal risk of neurovascular or lung injuries.ope

The buccofacial wall of maxillary sinus: an anatomical consideration for sinus augmentation

PURPOSE: This study aimed to quantify the thickness of the buccofacial wall of the maxillary sinus where sinus augmentations are often performed. MATERIALS AND METHODS: Fourteen sites located 15 and 20 mm superior to the anatomical cervical line (named as groups H15 and H20, respectively) and along the long axes of the mid and the interproximal of two premolars and two molars were measured from 74 Korean hemiface cadavers. RESULTS: The buccofacial wall of the maxillary sinus was thinnest at the area between the maxillary second premolar and first molar in groups H15 and H20. The lowest mean thickness was 1.2 mm in both groups. The walls were thicker in males than in females, with statistically significant gender differences found at four and two sites on the anterior horizontal reference in groups H15 and H20, respectively. However, the thickness did not differ significantly with age or laterality. Incomplete septa were found in seven of the 74 specimens, and they were present in the area between the first and second molars in six (86%) of these cases. CONCLUSIONS: These observations indicate that anatomical characteristics of the buccofacial wall thickness of the maxillary sinus need to be considered when performing a window opening procedure for sinus augmentation.ope

Trabecular bone ratio of mandible using micro-computed tomography in Korean

Cortical bone and trabecular portion play important roles in maintaining the general structure of bone. It has been reported that a decrease in bone mineral density is related with increasing age, sex, and teeth loss. However, most of the studies were done with conventional radiographic analysis. In addition, data from Korean population are rare. The aim of this study was to analyze trabecular pattern of the mandible using micro-computed tomography. Thirty-nine specimens of the mandible were prepared. Specimens were scanned with micro-computed tomography and reconstructed three-dimensionally. Sections were made parallel to the axis of each tooth. Trabecular bone ratio (TBR) was measured. Data were statistically analyzed with 1-way analysis of variance (alpha = 0.05). There was a statistically significant difference of TBR between dentate and edentulous mandibles in the molar region. Trabecular bone ratio of edentulous mandible in males was greater than that in females. Trabecular bone ratio of dentate mandibles reduced regularly with increasing age, whereas that of edentulous mandibles did not. It could be concluded that there were statistically significant differences in TBR according to presence of tooth, sex, and increasing age on specific areas.ope

Alveolar regions of the mandible for the installation of immediate-implant fixtures and bone screws of alveolar distractors.

The purposes of this study were to elucidate the anatomic relationship between the dental roots and surrounding tissues and to identify the optimal sites at which to install dental surgical devices including immediate-implant fixtures and alveolar distractors. We made 5 types of measurements on horizontal cross sections obtained at 1-mm intervals from 20 Korean mandibles. The following results were obtained: (1) the mandibular facial plate was thinnest at the canine (0.5-0.7 mm) and became thicker toward the molar region; (2) the thicknesses of the facial and lingual cortical bone in the interdental region increased from anterior to posterior and from coronal to apical aspects; (3) in each section, the buccolingual root was narrower than 4 mm at depths greater than 8 and 9 mm in the central and lateral incisors, respectively, and the maximum mesiodistal root widths were 3.0 and 3.3 mm; (4) the interroot distance increased from anterior to posterior and from coronal to apical aspects; and (5) on the sections of the first and second molars, the diameter of the septal bone ranged from 4.2 to 7.9 mm buccolingually and from 1.3 to 3.3 mm mesiodistally. Achieving successful placements of implant fixtures and bone screws requires an accurate understanding of the anatomic structure at the installation site. The reported anatomic data might facilitate successful treatments and provide crucial information for use when planning and performing placements of dental surgical devices.ope

Course and distribution of the lingual nerve in the ventral tongue region: anatomical considerations for frenectomy.

The aim of this study was to elucidate the sublingual and intralingual courses of the lingual nerve (LN) in the ventral tongue region, providing a clinical guide for safe surgical procedures such as frenectomy. We evaluated 16 specimens (32 sides) by gross observation after detailed dissections, and a further 6 specimens were examined after Sihler staining. All specimens were harvested from embalmed Korean cadavers. We classified the innervation patterns of the LN into 5 types and confirmed the distribution of the LN in the tip of the tongue. The classification of the LN was made with reference to a line formed by the interlacing of the styloglossus and genioglossus muscles. Based on the course of LN and the presence of a tiny twig (twigs directly innervating the ventral mucosa of the tongue, TM) directly innervating the sublingual mucosa, the course of the LN was classified as being straight, curved, or vertical and with or without the TM. Straight, curved, and vertical courses without the TM were seen in 9.4%, 46.9%, and 18.8% of the cases, respectively. Straight and curved courses with the TM were observed in 6.3% and 18.8% of the cases, respectively. Sihler staining revealed that the tongue tip is innervated by the LN. These findings indicate that surgical manipulations at the ventral tongue region might damage the LN and result in numbness of the tongue tip, and provide a useful anatomic reference for various surgical procedures involving the ventral tongue regionope

Variations in the trabecular bone ratio of the maxilla according to sex, age, and region using micro-computed tomography in Koreans

These cortical and trabecular bones maintain general bone structure. Bone mineral density (BMD) changes according to increasing age, sex, and teeth loss. From previous studies, the evaluation of BMD changes depended on conventional radiographic analysis. This study investigated the trabecular bone ratio (TBR) in maxillary bone samples based on data obtained by micro-computed tomography and estimated variations in BMD according to age, sex, and tooth loss. Thirty-eight specimens were scanned with micro-computed tomography and reconstructed three-dimensionally. Sections were made parallel to the axis of each tooth, and the TBR was measured. Data were statistically analyzed with 1-way analysis of variance and paired t-tests (α=0.05). The TBR differed significantly (P<0.05) in each tooth region in the dentate group but not in the edentulous group. The mean TBR was higher in men than in women. The TBR reduced more with increasing age in the dentate group than in the edentulous group. The TBR varies according to the presence of teeth, sex, and age in specific teeth regions.ope